The present invention relates to a method and an apparatus for non-invasive assessment of intracranial pressure.
The measurement of intracranial pressure (ICP) is an important tool in connection with diagnosing different health disorders, such as head injuries, stroke edema, intracranial hemorrhage, as an overpressure is potentially fatal. Traditionally, the intracranial pressure has been determined by drilling a hole in the skull and inserting a manometer. Needless to say that such an invasive method is potentially dangerous, not only as such, but also indirectly due to risk of infection. Accordingly, various prior art methods for non-invasive measurement of ICP have been proposed, some of which rely on inspection of the optical arteries which supply the eyes with blood. These arteries run from inside the skull to the eyes and are thus influenced by the pressure within the skull.
One type of such non-invasive method is disclosed in WO-A99/18386. In WO-A-99/18386 an ultrasonic transducer is brought into contact with the eye, the eye is put under slight pressure, and the blood velocity is measured in the intracranial and extracranial parts of the artery using Doppler measurement.
Another non-invasive method is disclosed in WO-A-2006/091811. In this method the artery is observed while pressure is increasingly applied to the eye, and it is determined when the artery collapses under the pressure.
Although being non-invasive, these methods involve pressure to the eye which is at best uncomfortable to the patient, but also is not entirely risk-free.